radardoug
Well-known member
Hey Bri, you were just calling him out, and for good reason. Hope you are having a good Xmas apart from that!
Proper wiring to avoid ground loops
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Brian Roth
Well-known member
@radardoug It's been OK.....better than last year... that was the first time in my life I was without my Mom (or any other family) at Xmas time. I am the last one still "above room temperature" in both the Roth and Thompson (Mom's side) portion of this genetic pool.
LOL....believe it or not, I decided to listen to Led Zepplin and ACDC Xmas day!
Bri
LOL....believe it or not, I decided to listen to Led Zepplin and ACDC Xmas day!
Bri
CalavoBob
Well-known member
A simple explanation of why it's best to choose the output end shield connection while lifting the destination (input) shield end is that amplification often takes place at an input. If the "telescoped" shield is connected there, the noise it is trying to take to Earth joins the grounding path of the input circuitry and dirties up the amplifying input stage. I think Bill Whitlock alludes to this in his detailed papers. Thomas Hay at MCI dicusses this in detail in the Nov 1982 issue of db magazine and in a paper delivered at the AES convention around that time.
CalavoBob
Well-known member
I forgot to mention, in those papers on studio grounding they point out putting balanced and any unbalanced gear you have into separate racks, and of course routing separate conduits for mic, line, power, digital, and telephone line signals. The earlier post from midnight arrakis is spot on about using balanced power if you can swing it.
radardoug
Well-known member
Nah, balanced power makes very little difference.
And the next post #39 is spot on about why balanced power is useless in the case of balanced equipment/connections.
Balanced power solves problems that should not exist to start with.
I had a client in LA that was building an immersive studio, and was quoted $150K for a balanced power system. He called me in a panic and I explained to his current electrician how to wire the studio, and then ordered him a 10KVA 220V to 110V transformer for $2K, had the electrician jump the phases together in the panel and he has never had a micron of noise in his studio. Not balanced, just isolated. When I worked for Record Plant Remote, we had the same thing. Every outlet was on one phase. Never had an issue. Balanced power involves grounding the center of a transformer, which makes no sense to me, accept it eliminates grounding problems that should be resolved correctly.
90% of problems come from having outlets on opposite phases, Remember that in your existing panel, every other breaker is on the same phase. Sometimes having an electrician move all your outlets to one phase and lamps, lights, microwaves and fridges to another gets rid of all the problems...
Actually, there is "balanced power" at the ready. In my NOLA flat, the range is connected to the 230V that jumps the two phases.
Rewiring the whole studio is another possibility with adequate plugs of course. Most of modern equipment is capable of 115/230V operation.
One would need to retain 115V outlets for itinerant gear.
I would not advocate anyway, just theorisizing.
Rewiring the whole studio is another possibility with adequate plugs of course. Most of modern equipment is capable of 115/230V operation.
One would need to retain 115V outlets for itinerant gear.
I would not advocate anyway, just theorisizing.
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Yep, free balanced power in the US if you run everything at 220VAC. A well known mastering studio does this. If there is a piece of gear that won’t operate at 220 they have AC step down boxes for that individual piece. There are giant isolation transformers at the mains entrance too.
This is a minor semantic point but the two polarities of 120V in residential mains power drops are considered the same single phase, in mains power parlance. Indeed the two legs of 230V power are opposite polarity. In the US multiple phases refer to single phase or three phase distribution. The three (actually four) separate wires on high power poles are carrying three different phases of power.
Studios wired for 230V outlets kind of defeats the lower (only 60VAC) benefit promised by "balanced" power.
JR
There are two types of power in the US. Single phase residential and three phase industrial. Since three phase has each hot leg 90 degrees out of phase this trick won’t work with three phase power.
Or I guess it would if you used the two legs 180 degrees out if phase. I’d ask a good electrician if that would work and meet code. Most don’t have access to three phase power.
Or I guess it would if you used the two legs 180 degrees out if phase. I’d ask a good electrician if that would work and meet code. Most don’t have access to three phase power.
OK. We have a similar distinction here, with two legs of 115V 180° apart called "diphasé" and anything with a different angle called "biphasé". Last time I saw "diphasé" was in 1976.
Lacking reference here. Does it refers to 115V balanced power being potentially less lethal than 115V unbalanced?Studios wired for 230V outlets kind of defeats the lower (only 60VAC) benefit promised by "balanced" power.
I have never seen or heard of anyone being seriously hurt by electrocution in a studio wired according to EU standards.
Same is not true for some live systems.
I am not familiar with that nomenclature.
In my judgement it's a good on paper marketing concept. Promoted for lower noise, not human safety.
I suspect 60VAC could still kill you but not as easily as higher voltage. Do not grab live 60VAC while sitting in your bathtub. The safety agencies get funny above around 30-40VAC (I am too lazy to look up the exact voltage ).
JR
Voyager10
Well-known member
So what is the theory behind 'balanced power'? (a) to reduce the amount of current injected by the connected equipment into mains ground (e.g. via 'class Y' capacitors), (b) reduce common-mode noise (i.e. on both the L and N lines) delivered to the connected equipment, (c) minimize the electrostatic field in the vicinity of the mains cable, (d) something else entirely?
MidnightArrakis
Well-known member
[So what is the theory behind 'balanced power'?] -- See Post #38.
/
That would possibly be the case for equipment with a pin 1 problem. The common mode to differential mode conversion I was describing from the figure in the Whitlock paper occurs even with properly designed equipment due to the physics of shielded cable.
Yes, and that is the dominant effect.
It does that because an isolation transformer is involved, but that would also be the case with traditional wiring of the secondary of an isolation transformer, so I don't think you can fairly ascribe that to the balanced
I don't have enough info to say one way or another on that point. That may depend on whether the entire studio is wired symmetric, e.g. might make a difference with electric guitars.
moamps
Well-known member
Now that you have so effectively driven away one member of the forum (which of course none of you will be sorry) in these days of exchange and mutual respect, I would just like to say, as I often do here, that I have used balanced power very successfully on several occasions. Of course, I did not create expensive black magic from it, but implemented it in cases where I had already installed an isolation transformer. As someone just hinted, symmetrical power also creates less EM interference in the environment, etc...
Tako je to kad se od šume ne vidi drvo.
Tako je to kad se od šume ne vidi drvo.
Have you noticed that this member, who decided to leave on his own volition, did not show any respect, and wrote a lot of misinformation?
I'd be curious to know what kind of set-up and what environment necessitated such extreme precautions.
I understand it would suit a test lab, but a typical music /broadcast studio would seldom justify it.
Why are you hiding behind your native language? This sentence translates very well in english, although it's often used in reverse, with the tree hiding the forest.
I don't know to whom it is addressed, maybe it's how you feel after reading this discussion...?
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moamps
Well-known member
There's no reason for you to be aggressive with me, Abbey. Just because I expressed my opinion.
The Dr was not very polite, but maybe part of the reason for that was that English might not be his native language, which is not the case for many members on the forum. My opinion is that everyone's opinion should be listened to and should be questioned too. There is no reason to reject ideas in advance without critical analysis, which is constantly being done here.
I implemented balanced power in several serious mastering studios, in several smaller production studios that had rather poor mains voltage quality, etc. At the time when I was more involved in recording club live jazz concerts, my entire setup was powered using an isolation transformer in a balanced connection.
The finding that a balanced power supply is unnecessary if the studio is correctly wired with balanced cables is often an oxymoron, how many mixers have you worked on that had balanced inserts...Furthermore, every more complex studio consists of at least one computer, and quite a number of devices with SMPS power supplies. In this sense, the quoted article from ePanorama is quite out of date.
I am not hiding from anything, but I am surprised that such experienced and old engineers on this forum have such a closed mind.
And finally, given that this discussion will probably end like the others, with your and JR's word being the last without the possibility of someone answering you, by abruptly closing the thread, I wish you all all the best in the New Year and a little more understanding and relaxation.
The Dr was not very polite, but maybe part of the reason for that was that English might not be his native language, which is not the case for many members on the forum. My opinion is that everyone's opinion should be listened to and should be questioned too. There is no reason to reject ideas in advance without critical analysis, which is constantly being done here.
I implemented balanced power in several serious mastering studios, in several smaller production studios that had rather poor mains voltage quality, etc. At the time when I was more involved in recording club live jazz concerts, my entire setup was powered using an isolation transformer in a balanced connection.
The finding that a balanced power supply is unnecessary if the studio is correctly wired with balanced cables is often an oxymoron, how many mixers have you worked on that had balanced inserts...Furthermore, every more complex studio consists of at least one computer, and quite a number of devices with SMPS power supplies. In this sense, the quoted article from ePanorama is quite out of date.
I am not hiding from anything, but I am surprised that such experienced and old engineers on this forum have such a closed mind.
And finally, given that this discussion will probably end like the others, with your and JR's word being the last without the possibility of someone answering you, by abruptly closing the thread, I wish you all all the best in the New Year and a little more understanding and relaxation.
